Paddling Tidal Passes

April-May 2003

This is an article from WaveLength Magazine, available in print in North America and globally on the web.
To download a pdf copy of the magazine click here: > DOWNLOAD

by David Pinel

The feathered arrow marks the direction of the flood current.
Current speed is in knots (kn).

Locations called 'Narrows', 'Pass', or 'Passage' are often a signal to kayakers of areas with moving water. The rise and fall of each tide cycle (linked with the gravitational pull of the moon and sun) forces large volumes of water through narrow areas between bodies of land. This can create very dynamic river like conditions on the ocean (hydraulics) that, unlike a river, continually change in size, intensity and direction. The basic skills and strategies for kayaking through restricted passages with moving water is best learned with an instructor or well-experienced guide. Your paddling decisions and tactics are determined by

  • speed of the current (predicted and observed)

  • your destination and direction of travel (with, against, or across the current)

  • channel characteristics (width, length, obstacles, depth, etc.)

  • the surface effect of any wind opposing the current

  • other boat traffic (number, size, restricted maneuvering, power)

  • your group size

  • your preparedness (experience, equipment, skills, and rescues).

Whenever current tables are available, use them instead of guessing from tide tables. It's NOT accurate to assume that the time of high or low tide corresponds with 'slack water' or minimal current flow through a channel. But even with the right tables, how should you decide the timing for a safe, fun, free ride with the 'tidal stream', or when to cross the current channel?

TEN TIPS FOR TIDAL PADDLING

  1. Refer to guide books, tide and current table maps, and consult paddlers and boaters familiar with the area to identify all channels with currents potentially over 1.5 knots (about 2.75 km/h). For trained novice and intermediate paddlers, anything over 1.5 knots can quickly become hazardous.

  2. Find those locations in the appropriate volume of the Canadian Hydrographic Service (CHS) Tide and Current Tables as either a primary reference station (main tables) or secondary station (adjustment tables in the back of the book).

  3. During daylight savings, always add one hour to the CHS prediction times in the reference tables.

  4. For secondary stations, follow the calculation instructions and examples provided by the CHS to determine the times when the current 'turns' (a.k.a. 'slack water') and when it's at the 'maximum' flow rate relative to the primary reference station.

  5. Using a chart or consulting local knowledge (people or guide books), determine the direction of the 'flood' current (when the water is filling inland areas) and 'ebb' current (when the water is emptying from inland areas) for each channel you plan to paddle. Flood directions are marked as feathered arrows on your chart. Also make note of shoreline geography that will affect water flow and direction.

  6. Choose to enter or cross a passage very close to the 'turn' time so that after the turn, the current will be flowing in your desired direction of travel.

  7. Stay to one side and clear of other boat traffic. If needing to switch shores quickly, cross the deepest part of the channel that other boats are likely to use, and do this in an area with clear visibility in either direction - it's not just kayakers who wait for the(ir) 'turn'!

  8. If the current flow rate is predicted to build to a maximum over1.5 knots, allow enough time to exit the passage (clear of whirls, overfalls, rips, eddies, etc.) before it reaches that rate, and allow a cushion of extra time for unforeseen delays.

  9. Learn the '50-90 Rule' for quickly predicting current speeds between the turn and maximum flow times. Divide the time period between the turn and maximum ebb or flood into thirds. By the end of the first third (usually approx. 1 hr. after the turn), the current will be at 50% of its maximum rate. At the end of the second third (usually approx. the 2nd hr. after the turn) it will reach 90% of the maximum rate. And in the last third, it only increases the remaining 10% to the maximum rate. This flow rate pattern is then reversed and eases toward the next turn (i.e. turn-50%-90%-100%- 90%-50%-turn).

  10. Once in the current, stay relaxed and loose in the hips, ready to brace, ready to paddle hard, and ready to grin from ear to ear. Keep a close eye on the shoreline to gauge your speed and progress on the shifting conveyor belt of water.

Nothing you read here can or should replace time spent with a competent instructor learning safe and effective predictions, paddling techniques and judgement in tidal currents. Learn to use the moon's gravitational pull to get one of the few 'free rides' available on the planet.

© David Pinel is Coordinator of North Island College's Coastal Adventure Tourism Program and guides with West Coast Expeditions, Kyuquot Sound. 250-830-0948. david.pinel@nic.bc.ca.